I have been working on a project for a few weeks- posters with a fair amount of body copy- large images, but smaller type whose legibility is the most important thing. I have set up a grid based on some of Brockmann's teachings in "Grid Systems".

I know that his and Bringhurst's method to construct a grid is set up for book spreads, with two adjacent pages. The margins are weighted proportonately to look harmonious on side by side pages, and obviously sit off-centered on the page.

Here's the question: If you are using a grid for a single page layout, how do you create margins that are centered, yet still look as elegant and proportionate as the double page grid system? How do you set up your margins on a page that is meant to function by itself? I know that there isn't a magic formula for this, but would like to know what dictates your page margins.

Thanks!!!